Arlington will start ground spraying for mosquitoes in three areas of the city, officials announced Friday, yet one more North Texas city to ramp up the offensive against West Nile virus.

Spraying will occur Sunday, Monday and Tuesday nights, weather permitting, between 10:30 p.m. and 4 a.m., around Jake Langston Park, Arlington Municipal Airport and Doug Russell Park, according to a city news release.

Also Friday, family members told the Star-Telegram that an 83-year-old North Richland Hills woman died Wednesday of West Nile-related encephalitis. Authorities have not confirmed the cause of death.

A daughter found Dorris Worsham, a retired teacher in the Keller school district, very ill inside her locked house Aug. 9. She was taken to a hospital, where she died.

Tarrant County Public Health officials said Friday that they had not received notification of Worsham's death. Physicians are asked to report deaths related to West Nile virus but are given a week to do so, an official said.

The agency has confirmed two such deaths this year, a Euless woman in her 60s and a Fort Worth man in his 80s. Both had underlying health conditions, officials said.

In Fort Worth, spraying of the insecticide permethrin began about 10:50 p.m. in parts of the 76104 and 76110 ZIP codes south of downtown. Weather permitting, trucks will spray again tonight and Sunday night, city officials said.

On West Magnolia Avenue, which bisects the area, a lively crowd was out about 10 p.m. enjoying milder weather.

Some were aware of the spraying to come but didn't care. Others were surprised to learn about it.

"That infuriates me," Marta Rozanich said.

She called it "chemical warfare."

"They've gone 20 years without spraying ... and I don't see any benefits versus the repercussions, especially for kids and pets," she said.

Jeanne Jones said that a night out with longtime friends took precedence over any fears.

"I've weathered many storms," she said. "This doesn't faze me. Some of my neighbors are staying in, but that isn't how I roll."

Last week, Arlington Fire Chief Don Crowson told the City Council that ground spraying was not the first line of defense against the virus but that the city could consider it "in a targeted way."

On Friday, he said in an e-mailed statement: "The city has been actively testing mosquitoes for a number of weeks and monitoring the results. We've been watching trends and reacting accordingly, and now we are at the point where targeted spraying in some places is the best option."

The city will use a low concentration of water-based permethrin in areas where larvicide and other measures have not worked.

"We're working to limit potential impacts of mosquito spraying on beneficial insects, fish, pets, and, of course, anyone who might be sensitive to the mosquito control agent," Crowson said.

Asked why the Fire Department was put in charge of the program, Crowson said the department is involved in issues that require logistical resources and public health issues.

“We’re pretty good at managing these sort of things,” Crowson said.

Worsham’s air conditioner had gone out last week, and she left windows open in her home, Reynolds said.

Worsham had a number of ailments, including diabetes, another sister, Gloria Dean said. But she still drove her own car and was sharp mentally, Reynolds said.

“By the time she had died, she had lost most of her brain function,” Dean said.

It took a few days in the hospital before West Nile encephalitis was diagnosed. Doctors drew spinal fluid and grew a culture to find the virus, which takes several days, he said.

“People need to know that this is a horrible way to die,” Worsham said. “The nerve system shuts down, you lose control of bodily functions, you’re unable to breathe on your own, unable to talk, unable to tell your loved ones how you feel.”

According to the Centers for Disease Control and Prevention, about one in 150 people who are diagnosed with West Nile infections are struck with the encephalitic variety.

The West Nile virus elicits a wide range of disease responses. Some people never develop symptoms after being exposed to the virus. For some others who do not die, exposure to the West Nile virus ruins their lives.

According to Jim Kennedy, a biology professor at the University of North Texas, the area may see a lull in West Nile virus cases. In Denton County, where there have been 96 human cases and one death, surveys have shown a reduction in the mosquito population and in the number of mosquitoes that are testing positive for the virus.

“Two months ago when we would sample the 12 sites around Denton, about half would be positive for West Nile,” Kennedy said. “In the past two weeks, maybe one or two sites have been positive. In the past week, no sites tested positive.”

If it rains this weekend however, that lull in mosquito population may quickly disappear as new mosquitoes fill the void, Kennedy said.

“We may see resurgence in the mosquito population,” Kennedy said. “I expect that mosquito populations will respond to these rains.”